In general, a mobile station accesses a base station (hereinafter referred to as a “serving base station”) and performs data communication with the serving base station, and when a receiving strength of a radio signal transmitted from the serving base station is insufficient, the mobile station performs a handover process. In this case, handover control signals such as a mobile station handover request (MSHO-REQ) message, a base station handover response (BSHO-RSP) message, and a handover indication (HO-IND) message need to be successfully exchanged between the serving base station and the mobile station in order for the mobile station to decide and perform the handover.
However, when the mobile station moves at a high speed, a handover process must be promptly performed. Transmission/receiving of the above-stated messages may include a handover delay time.
In addition, when the mobile station moves at a high speed, radio signal quality at a boundary area of a cell managed by the serving base station may be decreased, and the mobile station may move out the cell boundary area of the serving base station without successfully exchanging the handover control messages with the serving base station. In this case, the mobile station may select a random handover target base station (hereinafter referred to as a “target base station”) and request a handover from the target base station. However, when using a currently used method, the mobile station selects the target base station based on only a radio signal strength that is measured by a simple method.
Therefore, the mobile station may select a neighboring base station of the serving base station that is transmitting a radio signal with good quality but does not having sufficient radio resources, as a target base station, and the selected neighboring base station may not be able to accept the handover of the mobile station. This causes the mobile station to request a handover from another target base station, and accordingly a handover delay time is increased so that satisfactory service quality cannot be provided to a user.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.